By the summer of 1944, defeat was no longer a matter of opinion. The fall of Saipan severed the southern resource line; senior naval figures accepted there was no route back to parity. Yet Japan did not surrender for another year. The delay had many causes. The war had been launched without an exit plan, sustained by illusions of leverage. The strategy was trapped in a political order that prioritised preservation of the imperial institution, even as military options collapsed.

The weakness was visible before Pearl Harbor. The ‘Draft Proposal for Hastening the End of the War against the United States, Great Britain, the Netherlands, and Chiang’, adopted at the Liaison Conference between Imperial Headquarters, Japan’s highest military decision-making body, and the Japanese government on 15 November 1941, assumed – as the major premise for concluding the war that Japan was about to begin with the United States – that Germany, Japan’s ally, would force Britain into submission in Europe. If that happened, the United States would lose the will to continue the war, and Japan could bring the conflict to a draw. Premised on a German victory, it offered Japan no independent route out of the conflict. Written by junior officers and approved by the high command with barely a change, it reflected a system that could set war in motion without knowing how to conclude it.

By the time the plan’s limitations became obvious, Japan had already hollowed out much of its strategic capacity. Across the late 1930s and the early years of the war, factional battles sidelined many officers and diplomats who had argued for caution or realistic endgame planning. By 1945, effective decision-making rested largely with those bound to the original choice for war, leaving little institutional ability to adapt once the strategic floor gave way.

As reversals mounted – at Midway in June 1942 and then the Marianas – policy coalesced around the belief that one ‘decisive blow’ would force Washington to talk on terms short of unconditional surrender. When Okinawa, fought over brutally between March and September 1945, did not produce that leverage, the concept migrated to a projected homeland battle, Ketsu-gō. The reasoning became circular: fight on to gain bargaining power; invoke hoped-for bargaining power to justify fighting on.

The cabinet formed in April 1945 under Prime Minister Suzuki Kantarō tried to manage this bind. To keep a government intact that could still take decisions, Suzuki pursued a dual approach: publicly affirming total resistance to avoid provoking the army, while privately seeking a diplomatic exit. In June, with imperial authorisation, the Supreme War Council turned to Soviet mediation; on 12 July, Tokyo instructed Moscow Ambassador Satō Naotake, and later that month, at Emperor Hirohito’s prompting, it readied Prince Konoe Fumimaro as special envoy to carry an imperial letter to test Soviet willingness to mediate. Even so, the leadership could not settle on what to offer either Moscow or the Allies, reflecting the gulf between army optimists and civilian pessimists. By then, Soviet signals had cooled and the military situation was deteriorating too quickly for productive talks to take place.

Inside the court, the crucial broker was Kido Kōichi, Lord Keeper of the Privy Seal. Acting as the emperor’s political adviser, he drafted a war-termination plan in June, secured the emperor’s agreement to pivot from a decisive battle to diplomacy via Moscow, and then did the quiet work of aligning ministers and service chiefs behind that shift. Kido backed the Soviet track for domestic, not diplomatic, reasons: the army would not countenance a direct approach to London or Washington, whereas a Soviet channel was the only route they might accept while safeguarding the imperial institution.

Information flows mattered. General Umezu Yoshijirō, Army Chief of Staff, reported from Manchuria that units were depleted, shattering confidence in a decisive battle. Admiral Hasegawa Kiyoshi, dispatched by the emperor as an inspector, briefed him on the Navy’s desperate state: virtually all major fleet units were lost, leaving nothing substantial for homeland defence. Reports from within the imperial family, too – notably from Prince Morihiro Higashikuni, intelligence officer with the 36th Army and the emperor’s son-in-law – described decisive-battle formations short of even basic equipment, underscoring that a homeland fight could not yield the imagined bargaining power. Such assessments reinforced Hirohito’s move away from the last-ditch military solution.

Why persist with the Soviet route? Because Tokyo lacked authoritative knowledge that, at Yalta in February 1945, Stalin had agreed to attack Japan within two to three months of Germany’s surrender. It read the Neutrality Pact, the absence of open hostilities, and Stalin’s perceived brokerage role as grounds to try Moscow. Fragmentary intelligence suggested Soviet hostility, but the absence of hard confirmation allowed hope to survive. ‘Soviet mediation’ hardened into a near-unshakeable holding pattern – resting on a profound misreading. Hirohito persistently asked whether Japan’s approach had truly reached Stalin and Molotov; he was told it had – and that they had relayed Tokyo’s overture to Truman and Churchill – which he mistakenly took as evidence that the Moscow-centred peace track he had endorsed was making headway. Previously blacked-out and later-deciphered lines in Foreign Minister Tōgō Shigenori’s diary note that the emperor ‘appeared satisfied’ that Japan could now ‘press forward and speak in depth with the Soviets’, reinforcing the decision to stay the course even after the Potsdam Declaration of 26 July.

This was not for lack of potential alternatives: a Basel-based international central-bank hub used as a backchannel to US intelligence; neutral legations in Switzerland and Sweden; and, by mid-1945, a Vatican conduit. Tokyo noted them but did not mobilise any with urgency. The Emperor’s misjudged decision to bank on Soviet mediation kept policy fixed on Moscow, foreclosed other paths to peace, and squandered what little time remained.

August 1945 closed the circle. The atomic bombings and the Soviet entry into the war against Japan destroyed the already thin strategic calculus and extinguished the last diplomatic premise. With the Supreme War Council evenly split and formal leaders unable to coalesce, the Emperor’s seidan (‘sacred decision’) was invoked twice – on 10 and 14 August – to break the deadlock and accept the Potsdam Declaration. Even then, the Kyūjō Incident – an attempted coup to prevent surrender – saw rebels cut the Imperial Palace’s telephone lines and hunt for the gyokuon recording, the emperor’s pre-recorded surrender address (‘Jewel Voice Broadcast’), that was to be aired at noon on 15 August. Only Grand Chamberlain Tokugawa Yoshihiro’s concealment of the discs in a plain safe, and his endurance under rough handling, allowed the broadcast to proceed – showing how narrow the margin remained. Yet the very frame through which postwar Japan remembered ‘15 August’ obscured the fact that war with the USSR and its consequences ran on beyond that date.

Japan did not delay because defeat was unthinkable. It did so because the state had structured its war to preclude a timely exit: an endgame outsourced to Europe; strategy migrating into a ‘one-blow’ reflex long after it was untenable; a cabinet-service system unable to agree terms; and a palace that could broker a pivot but not multiply channels. At the apex, Hirohito’s decision to bank on Soviet mediation – rather than mobilise alternative neutral channels – compounded that drift, while the imperative to safeguard the imperial institution narrowed the space for useful and timely decision-making. When the reckoning came, it came by force of events.

Eighty years on, the lesson remains the same beyond Japan’s shores: when the terms for ending a war are left undefined, a state can drift towards defeat, with the choice of peace arriving only when the power to shape it has gone.